Page filter - can't get it to work

Question Status

I've created a new field on the Item card (Nav 2013), that allows free text entry, and have made it a visible column and available on the filter within the Item List page (31). I now need to filter by this column, but when I click on the filter, the dropdown shows the item number. How do I amend this so that the new field can be filtered (e.g. using wild card *)?